AES E-Library

AES E-Library

Integrated Circuits for High Performance Electret Microphones

Electret Condenser Microphones (ECM) are used in almost every consumer and communication audio application. The total yearly volume of all ECM's is well over 1 billion units. Over the years, innovation in ECM's have concentrated mainly on lower cost production and smaller sizes. Other improvements of sensitivity, Signal to Noise Ratio (SNR), linearity and supply current have not been addressed. In this paper several I.C. designs are presented, that replace the JFET inside the microphone canister. In a 2-wire ECM this IC results in 20dB increase in sensitivity and THD below 0.5% over the entire output range. In a 3-wire EMC, high PSRR of 60dB and low output impedance of 200 Ohm is achieved.